Not Applicable
Not Applicable.
This invention relates in general to hub assemblies for automotive vehicles and more particularly, to a new and improved cage for the bearing in the hub assembly to facilitate assembly of the hub assembly.
Many automotive vehicles of current manufacture have their road wheels coupled to their suspensions systems through hub assemblies which are supplied as package units ready for installation during the assembly of such vehicles. The typical hub assembly basically includes a housing of some type which is attached to a component of the suspension system for a vehicle, a hub to which the road wheel and also a brake rotor is secured, and a bearing between the hub and the housing to enable the hub to rotate relative to the housing with minimal friction. The bearing must accommodate thrust as well as radial loads and is preferably set to a condition of preload, so that the bearing operates without internal clearance; and the axis of rotation, as a consequence, remains stable. The typical hub has a spindle which extends into the bearing and a flange which projects radially from the spindle in front of the bearing and the housing which contains the bearing. The flange has parallel front and back faces which lie perpendicular to the axis of rotation and lead out to the very periphery of the flange. Threaded studs extend through the flange, projecting beyond its front face and through the brake rotor which is against the front face and the wheel which is against the brake rotor. The wheel and brake rotor are held against the front face of the flange by lug nuts which are threaded over the studs.
The wheel is typically supported on two rows of rolling elements with opposing angular contact to best oppose the moments placed on them in cornering. The wheel is typically attached to a hub on which bearing inner races are located. A suspension component that attaches to control arms, spring, and steering linkage (typically called a xe2x80x9cknucklexe2x80x9d) is the support for the bearing and the wheel. The bearing outer races are mounted to or within the knuckle. If the outboard inner race is an integral surface of the hub, and the rolling elements are tapered rollers, it is necessary to install the rollers to the hub with the cage holding the rollers inward. The necessity of installing the rollers first forces the seal to be pressed onto the non-rotating support where the tool must span a large radial distance in a very small axial space. The accuracy of seal placement cannot be assured with this tool design. When ball bearings are used, it is not necessary to install the balls on the inner race first. Due to their spherical shape, they can be easily held into a retainer that can be set into the outer race and the seal pressed without the hub being installed. This has not been possible with taper roller bearings.
Briefly, an improved hub and an improved bearing cage are disclosed which will allow for easier assembly of hub assemblies. As is common, in a hub assembly for coupling a road wheel to the suspension system of an automotive vehicle, the hub assembly comprises a housing, a hub, and a bearing located between the housing and the hub for enabling the hub to rotate with minimal friction relative to the housing about an axis X. The improvement comprises not only the bearing, but the incorporation of an outer raceway for the bearing into the hub, such that the hub actually forms a part of the bearing.
The bearing includes an inner race, an outer race, a plurality of tapered rollers positioned between the inner and outer races, and a cage for maintaining the positions of the rollers relative to each other in the bearing.
In one aspect of the invention, the cage comprises a large end ring, a small end ring, and a plurality of bridges spaced about the cage. The large and small end rings and the bridges define a plurality of pockets which receive the rollers. The cage further includes a large end member at the large end ring and a small end member at the small end ring. The large and small end members engage the roller at respective ends of the roller. The large end ring, small end ring, bridges, large end members, and small end members define pockets which fully entrap the rollers.
The large end member comprises a post which extends axially from the large end ring into the pocket. The large end post is sized to be received in a recess formed in the large end of the roller.
The small end member includes a bottom restraint which extends radially inwardly from the bridge radial inner surface. The bottom restraint has a radial inner surface spaced radially inwardly of the small end ring radial inner surface, an axial bottom surface, and side walls. The respective side walls of the bottom restraints and bridges in combination defining a groove which is sized and shaped to radially restrain an axial end of the roller in the bearing. Preferably, the bottom restraint and bridge side surfaces are curved giving the groove a continuous uninterrupted and smooth curved surface. However, the side walls could be oppositely tapered walls, forming a generally V-shaped groove.
The bottom restraint and bridge, in combination, maintain the radial position of the small end of the roller in the cage. The large end ring does double dutyxe2x80x94it both maintains the radial position of the large end of the roller in the cage and helps to maintain the axial position of the roller in the cage. The small end ring of the cage can also be provided with a small end post which extends axially into the pocket. The small end post is sized to engage the small end of the roller, and to work, in conjunction with the large end post, to maintain the axial position of the roller in the cage. If the roller is provided with a recess at its small end, the bottom restraint can be eliminated, and the two end posts, via their engagement with recesses in the ends of the roller, can operate to maintain the roller in the cage both axially and radially.
In another aspect of the invention, the hub assembly includes an inboard row of rollers and an outboard row of rollers, as well as inboard and outboard inner and outer races. At least one of the inboard and outboard inner races are formed integrally with the hub. Preferably, the outboard inner race is formed integrally with the hub, and the inboard inner race is formed in a cone received on the hub. With the outboard inner race being formed integrally with the hub, the hub also includes an integral thrust rib adjacent the outboard inner race.
The construction of the cage, and the formation of the outboard inner race as an integral part of the hub allows for the roller/cage assembly to be installed in the outboard position outer race before the seals and hub are installed in the hub assembly.
In an alternative embodiment of the hub, the hub includes a shoulder formed at the large end of the outboard inner race, the outboard inner race being integral with the hub. The cage includes a lip which extends from its large end ring and which is sized and positioned to engage the hub shoulder. The engagement of the cage lip with the hub shoulder restrains the cage against axial movement relative to the outboard inner race, yet allows the cage to rotate about an axis of the bearing assembly.
Another alternative construction for the cage is limited to the use of double row bearing assemblies. In such bearing assemblies, the bearing assembly comprising a double cup defining an inboard outer race and an outboard outer race, an inboard inner race and an outboard inner race; and an inboard row of rollers and an outboard row of rollers. The inboard and outboard row of rollers are held in inboard and outboard cages. The inner races can both be formed on cups. Alternatively, for use in the hub assembly of the present invention, one of the inner races (i.e., the outboard inner race) can be formed integrally with the hub spindle.
In another embodiment, for a double row bearing assembly, the inboard and outboard cages each include a connector extending radially from their respective small end rings. The connector includes a web extending from the small end ring of the cage and an end formation at an end of the web and which extends axially from the web. The connector of the inboard and outboard cages are positioned on the small end rings and are sized and oriented such that the end formations of the connector of the two cages engage each other to substantially prevent axial separation of the cages in the bearing assembly. Additionally, at least one of the connector is substantially circumferentially continuous, such that the end formations will not circumferentially catch each other, and the two cages can rotate relative to each other.